Addition of Encapsulated Soybean Oil and Waste Cooking Oil in Asphalt Mixtures: Effects on Mechanical Properties and Self-Healing of Fatigue Damage

Abstract

Embedded encapsulated rejuvenators have been proven to enhance the crack-healing ability of asphalt. This healing mechanism is autonomous as it is triggered by the energy resulting from the axles’ passages on the road: an advantage over other engineered healing methods. However, compared to the advances on crack healing by externally triggered methods, the understanding of the healing mechanism by the action of encapsulated rejuvenating agents is still evolving. Based on the findings of García et al. (2020b) on the optimum damage level to heal reflective cracking in asphalt mixtures with calcium-alginate capsules, this study further investigates the effect of different healing times (24, 48, and 72 h) on healing levels of fatigue-damaged asphalt mixtures. In parallel, the performance of encapsulated new soybean oil and waste cooking oil (WCO) is compared via their characterization and effects on the mechanical properties of asphalt. The embedded capsules decreased the resistance to moisture damage, stiffness, and durability of the base asphalt. Nevertheless, considerably greater self-healing indexes were observed, which were even more pronounced for longer healing times. In the field, these mixtures’ full healing capability would not be achieved at once as long periods of traffic closure are not feasible. Also, the asphalt deformation results in higher self-healing indexes due to the embedded capsules. Encapsulated WCO promoted the highest healing values, possibly because these capsules were more easily damaged and the oil better diffused into the asphalt.